Vomiting & Diarrhoea

GI Upset in Dogs Why does it happen?

This page is for information and reference purposes only. 

It is not a substitute for professional veterinary advice, diagnosis, or treatment.
Always speak to a qualified veterinary surgeon about your pet’s individual needs before starting, changing, or stopping any treatment.

GI Upset in Dogs (Vomiting & Diarrhoea)

What is GI Upset?

Gastrointestinal (GI) upset is one of the most common reasons dogs visit the vet. It usually involves vomiting, diarrhoea, or both. Most cases are mild and resolve quickly, but some can be serious or even life-threatening if the dog becomes dehydrated or has an underlying problem.

Why Does It Happen?
The digestive system is very sensitive. Common triggers include:

Dietary indiscretion (most common) — eating something they shouldn’t (rubbish, rich food, table scraps, grass).

Sudden diet changes or food intolerance.

Infections — viruses (e.g. parvovirus in unvaccinated dogs), bacteria, or parasites (worms, giardia).

Foreign bodies — swallowed toys, bones, socks, etc.

Toxins — chocolate, grapes, xylitol, plants, or chemicals.

Underlying diseases — pancreatitis, kidney disease, liver problems, food allergies, or Addison’s disease.

Stress, motion sickness, and certain medications can also cause vomiting.

Main Signs & When to Worry

Common signs:

Vomiting (food, bile, or froth)

Diarrhoea (may be watery, bloody, or very smelly)

Reduced appetite

Lethargy or tummy gurgling

See a vet immediately if your dog has:

Repeated vomiting (more than 3–4 times in a day)

Bloody vomit or diarrhoea

Severe lethargy or collapse

Signs of pain (whining, hunched posture)

Not drinking or keeping water down

Puppies, small breeds, or elderly dogs (they dehydrate very quickly)

gi upset in dogs
How We Treat GI Upset
Mild cases (often managed at home):

Starve for 12–24 hours (water only).

Bland diet for 3–5 days: boiled chicken + rice or a prescription gastrointestinal diet. Feed small, frequent meals.

Gradually return to normal food over 4–5 days.

Probiotics and gut protectants (e.g. kaolin or slippery elm) may help.

Moderate to severe cases (vet treatment):

Anti-sickness injections

Anti-diarrhoea medication.

Fluid therapy (subcutaneous or intravenous) to correct dehydration.

Blood tests, X-rays, or an ultrasound to find the cause.

Antibiotics or antiparasite treatment if needed.

Take-Home Messages

Most simple cases of vomiting and diarrhoea settle within 24–48 hours with rest and a bland diet.

Never give human medicines (especially Imodium or ibuprofen) without vet advice — they can be dangerous.

Prevention is better: keep rubbish and toxins out of reach, feed a consistent diet, and stay up to date with vaccinations and worming.

Puppies and small dogs can go downhill very fast — don’t wait more than a few hours if they are unwell.

Repeated episodes may indicate a chronic problem that needs investigation.

Pro tip: Keep a packet of plain cooked chicken and rice in the freezer for emergencies, and always have your vet’s out-of-hours number handy

This information is for reference only and should not replace advice from a qualified veterinary surgeon. Always speak to your vet before starting, changing, or stopping any treatment for your pet.

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